The present invention relates to an improved structure in the electric plug used in telecommunication, and especially relates to a plug of which the electromagnetic wave shielding sheet can be automatically produced, and the shielding area against electromagnetic waves can be increased to provide better quality and reliability.
Communication instruments such as the computer, telephone, FAX machine, district network equipment etc. which take advantage of electronic communication all have plugs and sockets for telecommunication. Such instruments are generally provided with parts which include lug and socket for connecting with another plug provided on the end of a conductor. Such products can often be adversely affected in their function as well as the quality thereof by electromagnetic waves or static electricity, which can impede the transmission of information. A device is needed to prohibit electromagnetic waves as well as static electricity.
A plug for telecommunication equipment is generally ejection molded from plastic to form a main body. The outside periphery thereof is enveloped at an appropriated position with a shielding sheet material to perform the above mentioned function of prohibition of electromagnetic wave. Such shielding sheet normally is made of metallic material which can ground the electromagnetic wave and the static electricity, so as to eliminate the interference of electromagnetic wave or static electricity.
The primary defects of the existing plugs for telecommunication reside in that: the shielding area is too small; and the connection between the shielding sheet and the main body must be effected manually. We are now citing a drawing (FIG. 1) to illustrate the conventional structures:
Referring to FIG. 1, the conventional plug for telecommunication comprises a main body 10 molded integrally from plastic, a metal shielding sheet 11 envelops the outside periphery thereof. The shielding sheet 11 covers generally the rear half of the sides of the main body 10. The front ends of both sides of the shielding sheet 11 are provided with elongated connecting lugs 12 conforming in shape with that of both sides of the main body 10. Two short tongs 13, 14 are provided separately and are behind and at a slightly higher position of the lugs 12.
The short tongs 13, 14 extend vertically upward before the shielding sheet 11, 13 fixed on the main body 10. After the main body 10 and the shielding sheet 11 are joined, the tongs 13, 14 are bent down to a present position (as shown in FIG. 1). Such a structure has at least the following defects:
1. The tongs 13, 14 are very small, and are located in a narrow area. They are difficult to be put into place by a machine.
2. The tongs 13, 14 are conventionally manually bent down gradually from the vertical position. This is wasteful in labor cost.
3. Since the main connecting structure is operated by manual force, the quality thereof is difficult to control.
4. Due to the variations of the quality of the connection, the quality of the conventional structure is uneven. It can be subjected to possible interference with communication transmitting, and the reliability is quite low.
Besides the above mentioned defects, the total shielding area is relatively small, thereby reducing its effectiveness.